I have to heavily stress the appropriateness of Computer Science Unplugged. While technically oriented toward younger students, it's absolutely appropriate for an older adult learner without a computer. If he can learn the material in CS Unplugged front and back, and understand it perfectly, he'll be
very well placed for starting a career in programming when he gets out. Many programmer interviews are based on the materials that this book covers.
And it's just a book, and all exercises in it can (and should) be done with no computer.
Once he works through this, send him a copy of SICP: https://mitpress.mit.edu/sicp/ Covers some of the same material at a much higher level, and more.